Saw palmetto is not finasteride just take the propecia if your going to go down that route. The propecia is actually strong enough to help your hair. I would wait though on propecia if I was 17.
Yeah you hair def looks like it receding reminds me of mine when mine went but i was also balding at the front aswell and it joined up in the end (the widows peak kept receding and joined with the bald patch at the front what caused a island sort off speak) you may be one of the lucky ones and it just stays like that and just have a widows peak because loads of peoples hair goes like that but IF it does comes to the worst then dont worry dont do what i did and worry when mine started going at 16 (im 20 now and im fine with it i dont care nomore) dont worry.